Reusable structure for forming joints in concrete

ABSTRACT

A two-part groove-molding structure for forming a joint in a freshly poured concrete roadway or the like; one part being a metallic U-shaped envelope having an open top and a bottom bight portion of less cross-sectional thickness than the sidewalls and hingedly connecting such walls so that they tend to collapse together; the other part being a flexible wedge inserted within the envelope and gripped by knurled inner surfaces on the upper portions of the sidewalls, the wedge having an enlarged head laterally overlying the sidewalls and producing chamfered edges on the walls of the groove and the head having a bulged top for indicating proper placement of the structure in the concrete.

United States Patent [72] lnventor William F. Middlestadt Rte. 2, Box 330, Arnold, Md. 21012 [21] Appl. No 697.063 [22] Filed Jan. 11.1968 [45] Patented June 29, 1971 54] REUSABLE STRUCTURE FOR FORMING JOINTS lN CONCRETE 3 Claims, 4 Drawing Figs.

[52] US. Cl 249/9, 25/118. 94/51, 249/98, 249/150 [51] Int. Cl E0lc 11/04 [50] Field of Search 249/9, 98, 112,173,183,146,150,188;94/51;25/118 W, 1 18 D, 1 18.5

[56] References Cited UNITED STATES PATENTS 1,539,341 5/1925 Wieberg 249/9 1,891,897 12/1932 Fischer 94/51 Primary Examiner-.1. Spencer Overholser Assistant Examiner-Ben D. Tobor Att0rney-Stowell & Stowell ABSTRACT: A two-part groove-molding structure for forming a joint in a freshly poured concrete roadway or the like; one part being a metallic U-shaped envelope having an open top and a bottom bight portion of less cross-sectional thickness than the sidewalls and hingedly connecting such walls so that they tend to collapse together; the other part being a flexible wedge inserted within the envelope and gripped by knurled inner surfaces on the upper portions of the sidewalls, the wedge having an enlarged head laterally overlying the sidewalls and producing chamfered edges on the walls of the groove and the head having a bulged top for indicating proper placement of the structure in the concrete.

REUSAIELIE STRUCTURE lFGR FORMING ,lOllNTS IIN CONCRETE BACKGROUND OF THE INVENTION This invention appertains to the formation of joints in a settable composition, such as concrete, in the construction of a roadway, pavement or the like and more particularly relates to a novel and improved reusable structure for molding a groove in such composition, as it sets, so that, after the composition has set, the structure can be removed therefrom and the resultant groove can be filled with a suitable sealant.

The formation of such groove in a setting concrete bed by using a molding structure, that is, inserted in the freshly poured concrete mix and removed after the concrete has become set, is known in the art.

One example of such structure is shown in my prior US Pat. No. 3,297,294, issued Jan. 10, 1967. Such patent discloses a metallic envelope that tapers from the top portion to the rounded bottom, with the top portion being formed by the overlapping and interlocking inturned upper edges on the sidewalls of the envelope. The envelope is not internally supported and the interlocked edges provide the sole means for holding the sidewalls in their spread apart placement during the setting ofthe concrete.

An example of an internally supported molding strip is shown in the U.S. Fat. to J. M. Cummings, No. 3,052,945, issued Sept. Il, 1962. The joint former, disclosed in such patent, consists of a plastic V-shaped mold and a plastic spreader which is wedged between the upper edges of the sidewalls of the mold. The sidewalls are joined at an apex juncture at the bottom, such apex juncture being of a particular and considerable thickness, in relation to the thickness of the sidewalls, so that the mold can be easily inserted in the poured concrete, so as to reinforce the walls in resisting the compressive force of the surrounding concrete, and so that a contractual elasticity will be imparted to the walls to force them into a normal closed, rather than spread apart, position.

While the use of a two-part structure, one part being an internal wedge support, has proven desirable, structures, such as that shown in the Cummings patent, have been found to have drawbacks, particularly in two important respects.

Such structures tend to float in the concrete mix. This creates a serious problem, since final finishing of the concrete bed will bring concrete up to the top of these raised inserts, leaving high ridges of concrete at the final joints.

Such structures are very difficult to remove unless the joints have functioned, that is, contracted and moved apart, because of the solid plastic at the base of the mold part. Such solid base or apex portion offers no flexibility, inward and away from the set concrete, to the sidewalls. Thus, the mold inserts are very difficult to remove from the set concrete and it has been necessary to use considerable extracting force, applied directly to the inserts. However, such inserts are often not strong enough to withstand such force that must be employed to remove them from the set concrete, with the result that after only a couple of reuses they become cracked and are of no further value. Considering that such mold inserts have an initial cost of approximately 30 to 50 cents a foot, it can be appreciated that the employment thereof is not economically sound, where only several reuses can be realized because of failure of the inserts.

In the road construction industry maintenance of labor and material costs at the lowest level, consanant with well laid and good functioning roadways, is of extreme importance. Thus, the use of unnecessary man-hours in removing the mold inserts and the inability to reuse he rather expensive inserts over a productive period of time constitute serious drawbacks. When this is coupled with the problem of floating, it can be seen that such structures have serious defects.

THE INVENTION Accordingly, a primary object of the present invention is to provide a reusable structure for forming joints in concrete, which structure is intended to overcome the shortcomings associated with known reusable joint structures.

Another important object of the present invention is to provide a joint-forming structure that will maintain its inserted position in the poured concrete and will not float or twist therein and that can be easily withdrawn from the set concrete with a minimum of manual and mechanical force and without being damaged so that it can be reused repeatedly.

A further important object of the present invention is to provide a two-part joint-forming structure that can be easily and properly placed in the poured concrete, due to the construction of the mold part and the incorporation in the wedge part of a placement indicator; that will be resistant to longitudinal twisting and to the compressive force of the surrounding concrete, as it hardens, so that the desired size and shape of the groove will be obtained; that can be easily withdrawn from the set concrete, due to the inherent, collapsing flexibility of the mold insert after the wedge is removed therefrom; and that will form a groove having its open end shaped so that extruded type sealants can be easily installed in the groove and so that the edges of the open end will not generally chip.

The foregoing and ancillary objects, including the provision of an inexpensive, reliable, efficient and repeatedly reusable joint-forming structure, are attained by the present invention, the preferred embodiment of which is set forth in the following description and illustrated in the accompanying drawing, wherein:

FIG. l is a vertical section of the upper portion of a concrete slab, showing the fully inserted joint-forming structure of the present invention in vertical section;

FIG. 2 is a view similar to FIG. I, but showing the mold insert with its sidewalls converged together, as it appears after the wedge has been removed and prior to the withdrawal of the mold insert;

FIG. 3 is a view similar to FIG. 1, but showing the formed groove, as it is being filled with an extruded-type sealant, and,

FIG. 4 is an exploded perspective showing of the two-part mold-forming structure.

Referring now more particularly to the drawing, and initially to FIG. 4 thereof, the joint-forming structure 10 is composed of two parts 12 and M. The part 12 constitutes the insert mold, while the part 14 serves as a wedge spreader and internal support therefor, in its functioning condition.

The part 12 is formed from a smooth corrosion-resistant metallic sheet which is thick or heavy enough relative to its surface area to prevent floating of the forming structure by weight alone A sheet of 30-gauge mild steel has proven satisfactory, but the gauge of the metal employed must be approximately 30-gauge or more.

The metallic sheet is folded upon itself to provide a hollow U-shaped envelope 16, which has planar sidewalls l8 and 20 that are hingedly connected by a bottom bight portion 22. The sidewalls have smooth outer surfaces that are resistant to bind ing or adherence to the setting concrete. The exteriorly smooth bight portion 22 is smoothly rounded in transverse cross section. The cross-sectional thickness of the bight portion 22 is considerably less than the cross-sectional thickness of the sidewalls 18 and 20 so tat the bight portion acts as a hinge between the sidewalls, preventing loss of shape of the sidewalls and assuring easy removal of the part 12, as will be described In the normal relaxed or unused position of the envelope 16, as shown in FIGS. 2 and 4, the sidewalls 18 and 20 have lower portions 24 and 26 which are in parallel relation. The lower portions extend from juncture portions 28 at the bight portion 22, the juncture portions being smooth flareouts at the side edges of the bight portion and smoothly emerging into the lower portions 24 and 26 of the sidewalls. The sidewalls also have upper portions 30 and 32, which, in the uninst alled or normal relaxed position of the envelope, are

mutually inclined inwardly and have converging outer free edges 34 and 36 that are in touching contact.

The part 14 consists of a wedge 38 formed from a block or strip of flexible material. Any suitable material may be used, such as rubber or rubberlike synthetic material. The wedge 38 has a body 40 provided with a tapered lower end 42 for spreading the contacting edges 34 and 36 of the sidewalls of the envelope 16 apart in the insertion of the wedge body between the upper portions 30 and 32 of the sidewalls. .The body 40 has opposing flat sides 44 and 46 which are adapted to be engaged and gripped by the inner surfaces 48 and 50 of the upper portions 30 and 32 of the envelope sidewalls l8 and 20.

In order to prevent relative longitudinal movement between the installed parts 12 and 14 and to thereby eliminate twisting of the inserted structure 10, an interlocking means is provided between the upper portions 30 and 32 of the sidewalls of the envelope l6 and the sides 44 and 46 of the wedge body 40. Such interlocking means consists ofa series of small ridges 52 formed on the inner surfaces 48 and 50 of the upper portions 30 and 32. By so knurling or otherwise roughening the inner surfaces, the upper portions 48 and 50 will securely grip the sides of the wedge body.

The wedge 38 has an enlarged head 54 formed on the top of the 58 40. The head has side wing portions 56 and 58 which, when the wedge is structurally associated with the envelope 16, installed in the poured concrete, as shown in FIG. 1, laterally overlie the sidewalls of the envelope. The wing portions 56 and 58 have upwardly and outwardly inclined under surfaces 60 and 62 having shoulders 64 formed at the inner edges thereofat the sides 44 and 46 of the wedge body 40. The shoulders 64 are normal to the sides 44 and 46 and seat on the edges 34 and 36 of the upper portions 30 and 32 of the envelope sidewalls 18 and 20 so as to locate the wedge body in the envelope. The outer edges 66 of the wing portions are parallel to the sides of the body.

The head 54 is formed with a bulged top that extends longitudinally of the wedge and serves as an indicator for indicating proper placement of the assembled structure in the poured concrete. The head is formed with a longitudinal cavity 70 that underlies the bulged indicator and permits it to collapse inwardly so that it will not interfere with surface finishing of the setting concrete.

In use, the wedge 38 is inserted within the envelope 16 so that the structure 10 has an assembled appearance, as shown in FIG. 1. The structure 10 is inserted into the poured concrete 72 until the indicator 68 is located slightly above the upper surface 74 of the concrete, as shown in FIG. 1. At such point, the structure 10 is properly positioned, with the undersurfaces 60 and 62 of the wing portions 56 and 58 of the wedge head 54 seated in the upper surface 74 of the concrete.

As shown in FIG. 1, the wedge body 40 fits snuggly between the upper portions of the sidewalls l8 and of the envelope and spreads the sidewalls apart so that the lower portions 24 and 26 are inclined outwardly and the upper portions and 32 are in parallelism. The wedge body 40 directly braces the upper portions of the sidewalls and absorbs all of the compressive force of the surrounding concrete 72 so that there is no stress on the sidewalls of the envelope. The wedge body places a potential load or energy on the bight portion 22 which reacts when the wedge is removed, as will be described.

The head 54 of the wedge seats in the upper surface 74 of the concrete above the envelope and the under surfaces of the inserted wing portions 62 and 64 impart their shape to the concrete above and laterally away from the sides of the inserted envelope 16.

After the structure 10 is inserted in the concrete 72, as shown in FIG. 1, the surface 74 of the concrete 72 is finished in the usual manner. The concrete is then permitted to set and, after the concrete has become hardened, the structure 10 is removed. ln removing the structure 10, the wedge 38 is pulled out from the envelope 16. When the wedge has been completely removed from the envelope, the sidewalls l8 and 20 of the envelope close together, due to the spring hinge connection provided by the particular bight portion 22. The envelope 16 then assumes the relaxed position, as shown in FIG. 2. The edges 34 and 36 are in contact and the upper portions 30 and 32 of the sidewalls 18 and 20 are converged inwardly with the lower portions 24 and 26 in parallelism. The outer surfaces of the sidewalls are withdrawn out of contact with the walls 76 of the formed groove 78. Aiding in this is the smoothness of the exterior surfaces of the metallic sidewalls 18 and 20, since they do not tend to adhere to the setting concrete. The collapsed envelope 16 can then be easily gripped and withdrawn from the groove 78 leaving the open groove, as shown in H6. 3.

The groove can then be filled with a suitable sealant. The groove has chamfered edges 30 on its sidewalls so that an extruding device 82 can be easily positioned in filling relation with the open top of the groove to extrude a sealant 84 therein as shown in FIG, 3.

The chamfered edges on the sidewalls 76 of the groove not only permit easy installation of extruded-type sealants but also eliminate subsequent chipping of the upper portions of the sidewalls of the groove.

From the foregoing description of this invention it will be seen that the joint forming structure provides a very inexpensive means for forming uniform joints in a concrete or the like slab and that the construction of the joint-forming structure will enable it to be easily inserted into the poured concrete and removed from the set concrete with a minimum of labor costs and in a manner so that the structure can be repeatedly and reliably reused.

While the preferred form of the present invention has been described herein and illustrated in the accompanying drawing, such is merely by way of example since changes in construction and environmental usages will occur to those skilled in the art as come within the spirit and scope of the appended claims.

What I claim is:

l. A reusable mold structure for forming a groove in a freshly poured concrete or similar settable composition mix in the formation of an expansion joint in the set concrete, said structure comprising:

a metallic sheet folded upon itself to form an elongated, substantially U-shaped envelope adapted to be bodily lowered into a freshly poured concrete mix, said envelope in its undistorted condition including opposing sidewalls, having lower planar and parallel portions and upper, inwardly inclined, planar portions terminating in free contacting edges, and a bottom bight hingedly connecting the lower portions of the said sidewalls, said bight portion normally biasing the sidewalls toward each other, and a flexible wedge inserted between the upper sidewall portions, said wedge having a body formed with a tapered lower end for spreading the edges of the upper wall portions apart during the insertion of the wedge, said wedge having flat, substantially parallel sides engaged by the inner, facing surfaces of the said upper wall portions, and means for increasing the frictional engagement between the wedge and the inner, facing surfaces of the upper sidewall portions, the means for increasing the frictional engagement between the wedge and the upper sidewall portions is defined by roughened areas on the said inner surfaces of the said upper wall portions.

2. A reusable mold structure for forming a groove in a freshly poured concrete or similar settable composition mix in the formation of an expansion joint in the set concrete, said structure comprising:

a metallic sheet folded upon itself to form an elongated, substantially U-shaped envelope adapted to be bodily lowered into a freshly poured concrete mix, said envelope in its undistorted condition including opposing sidewalls, having lower planar and parallel portions and upper, inwardly inclined, planar portions terminating in free contacting edges, and a bottom bight hingedly connecting the the wedge and the inner, facing surfaces of the upper sidewall portions, said wedge having an enlarged head formed thereon and having upwardly and outwardly extending side wing portions laterally overlying the edges of the said upper wall portions, said wing portions having upwardly and outwardly inclined under surfaces adapted to rest in the concrete mix and form chamfered outer edges on the walls of the formed groove in the set concrete, said enlarged head having a bulged top portion running longitudinally along said wedge and defining an indicator means for indicating proper placement of the envelope and wedge in the concrete mix.

3. The structure of claim 2 wherein a longitudinal cavity lies beneath and contiguous to said bulged top portion, whereby the bulged portion is collapsible inwardly and downwardly. 

1. A reusable mold structure for forming a groove in a freshly poured concrete or similar settable composition mix in the formation of an expansion joint in the set concrete, said structure comprising: a metallic sheet folded upon itself to form an elongated, substantially U-shaped envelope adapted to be bodily lowered into a freshly poured concrete mix, said envelope in its undistorted condition including opposing sidewalls, having lower planar and parallel portions and upper, inwardly inclined, planar portions terminating in free contacting edges, and a bottom bight hingedly connecting the lower portions of the said sidewalls, said bight portion normally biasing the sidewalls toward each other, and a flexible wedge inserted between the upper sidewall portions, said wedge having a body formed with a tapered lower end for spreading the edges of the upper wall portions apart during the insertion of the wedge, said wedge having flat, substantially parallel sides engaged by the inner, facing surfaces of the said upper wall portions, and means for increasing the frictional engagement between the wedge and the inner, facing surfaces of the upper sidewall portions, the means for increasing the frictional engagement between the wedge and the upper sidewall portions is defined by roughened areas on the said inner surfaces of the said upper wall portions.
 2. A reusable mold structure for forming a groove in a freshly poured concrete or similar settable composition mix in the formation of an expansion joint in the set concrete, said structure comprising: a metallic sheet folded upon itself to form an elongated, substantially U-shaped envelope adapted to be bodily lowered into a freshly poured concrete mix, said envelope in its undistorted condition including opposing sidewalls, having lower planar and parallel portions and upper, inwardly inclined, planar portions terminating in free contacting edges, and a bottom bight hingedly connecting the lower portions of the said sidewalls, said bight portion normally biasing the sidewalls toward each other, and a flexible wedge inserted between the upper sidewall portions, said wedge having a body formed with a tapered lower end for spreading the edges of the upper wall portions apart during the insertion of the wedge, said wedge having flat, substantially parallel sides engaged by the inner, facing surfaces of the said upper wall portions, and means for increasing the frictional engagement between the wedge and the inner, facing surfaces of the upper sidewall portions, said wedge having an enlarged head formed thereon and having upwardly and outwardly extending side wing portions laterally overlying the edges of the said upper wall portions, said wing portions having upwardly and outwardly inclined under surfaces adapted to rest in the concrete mix and form chamfered outer edges on the walls of the formed groove in the set concrete, said enlarged head having a bulged top portion running longitudinally along said wedge and defining an indicator means for indicating proper placement of the envelope and wedge in the concrete mix.
 3. The structure of claim 2 wherein a longitudinal cavity lies beneath and contiguous to said bulged top portion, whereby the bulged portion is collapsible inwardly and downwardly. 